A decision support tool to prioritize ballast water compliance monitoring by ranking risk of non-indigenous species establishment

Each year, Journal of Applied Ecology awards the Southwood Prize to the best paper in the journal by an author at the start of their career. In this post, Dr. Johanna Bradie (University of Windsor, Canada) discusses her shortlisted paper which reports the development of a decision support tool, known as a ballast water invasion probability tool, which automatically quantifies the risk of non-indigenous species associated with individual ships, using information readily available on ballast water reporting forms that ships are required to submit to Transport Canada.

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Photo: Dr. Johanna Bradie

Invasive species are one of the main contributors to biodiversity loss globally, and international shipping is a major vector for aquatic invasions. In transiting from port to port, ships must load and unload ballast water to maintain trim and stability as they conduct cargo operations. Globally, shipping operations move over 10 billion m3 of ballast water and the biota contained therein annually.  This provides an expeditious transfer mechanism for species to move around the globe.

To combat the introduction of invasive species, the International Maritime Organization established a set of standards which aims to limit the number of organisms that can be discharged in ballast water. Most ships have already installed, or will need to install, a ballast water management system that reduces concentrations of organisms in ballast to meet acceptable discharge standards.

Prior to the use of ballast water management systems, ballast water exchange was commonly used to reduce risk of invasive species establishments. Ballast water exchange is a process whereby ships exchange their ballast water in the middle of the ocean to reduce the chance that they will carry organisms likely to establish at the destination port.

In Canada, Transport Canada inspectors are tasked with monitoring ships for compliance with shipping regulations. Since they are only able to inspect a sample of incoming ships, it makes sense to direct management efforts to those ships that are most likely to pose a risk of biological invasion. Together with Dr. Sarah Bailey, I developed a decision-support tool that informs on the relative risk of a ship carrying species likely to establish based on biological knowledge about factors that increase establishment likelihood.

Indeed, our tool combines information on two of the main factors affecting establishment success: 1) a species’ capacity to survive in its introduced environment, and 2) the number of individuals being introduced, also known as propagule pressure. This tool was incorporated into Canada’s Ballast Water Database such that necessary information on incoming ships is automatically extracted from ballast water reporting forms (which are required for all incoming vessels) and port inspectors receive a report ranking each ships biological risk together with other details regarding their day-to-day operations.

This tool is a great example of a way to bridge the gap between science and management, such that inspectors on the ground are able to implement the best available science knowledge in their daily decision-making.

Read the full paper A decision support tool to prioritize ballast water compliance monitoring by ranking risk of non-indigenous species establishment in Journal of Applied Ecology

Find out more about the Southwood Prize early career researcher award here.

Dr. Johanna Bradie is an NSERC post-doctoral fellow at the Great Lakes Institute for Environmental Research at the University of Windsor, Canada. She is a data scientist who specializes in forecasting models and machine learning and is broadly interested in using analytics to inform decision-making.  Johanna’s recent work has focused on supporting science policy to reduce the introduction of aquatic non-indigenous species via ballast water. More specifically, she has used predictive modelling to evaluate alternative regulatory options to inform legislation and evaluate the consequences of ballast water management failure.

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